1. Field of the Invention
The present invention generally relates to a centrifugal separator, and more particularly to a centrifugal separator able to function as an agitator.
2. Description of the Related Art
In a process, for use in a clinical inspection, for analyzing substances and a process for isolating DNA (Deoxyribonucleic Acid) by using the gene manipulation technique, mixing of the samples and reagents and centrifuging of the reaction products are alternately repeated many times. In the usual operations, a sample container such as a test tube is manually or semi-automatically transferred between the agitator and the centrifugal separator. On the contrary, in gene manipulation techniques, it is desired that the sequence of operations be fully automatically carried out under a condition of biological containment in order to prevent biohazards from spreading. Accordingly, if the centrifugal separator has the function of the agitator, it is possible to simplify the automatic transfer mechanism in the fully automatically analyzing or isolating apparatus, since there is no need for transfer of the sample container between the centrifugal separator and the agitator.
In Japanese Laid-Open Utility Model Publication 59-193527, there is shown a centrifugal separator having a function of an agitator. The centrifugal separator has a rotor on which container holders for a plurality of sample containers are hung swingably in a radial direction of the rotor. The rotor is operated to rotate intermittently. During the rotation of the rotor, the sample container held by the holder swings and its lower end is lifted by generated centrifugal force. When the rotation of the rotor stops, the swung up lower end of the container is returned to the initial position and then it is caused to collide against a stopper which is arranged around the main body of the rotor and also radially inside the container holders so that the content of the container is agitated by the shock resulting from the collision. Of course the centrifuging is performed by the continuous rotation of the rotor.
However, such shock resulting from the collision is too strong for the agitating desired in the isolation of DNA. Therefore the centrifugal separator disclosed in the above Publication is not applicable to the isolation of DNA. The agitation should be smoothly performed for the isolation of DNA to avoid the breakdown of the DNA which is very weak in its resistance to mechanical force.